Information retrieval method and relay center

ABSTRACT

Base station BS adds a base station ID for specifying itself to a signal transmitted from mobile station MS. Data distribution management unit GWS 3  of gateway server GWS extracts the base station ID added to a GET request and reads out an area name corresponding to the base station ID from area name conversion table TBL. Data distribution management unit GWS 3,  using the area name as a search key, searches location-related information database GWS 4  for location-related information corresponding to a present location of mobile station MS and transmits the information to mobile station MS.

TECHNICAL FIELD

[0001] The present invention relates to a relay center and aninformation retrieval method for searching information on a network byusing location information of a mobile station.

BACKGROUND ART

[0002] In recent years, in a mobile communication network using cellulartelephones, a system for acquiring a present location of a mobilestation (hereinafter referred to as location information) has steadilybecome commercially viable An example of such a system is as follows. Ona PHS (Personal Handy Phone System; Registered Trademark) network a basestation receives radio waves from a mobile station and is able todetermine an approximate present location of a mobile station on thebasis of the location of the base station. Another method which has beensuggested for acquiring location information of a mobile station is byutilizing a mobile station having a GPS (Global Positioning System)installed. Possible uses of this location information are, for example,services such as showing the location of a mobile station over a map ona display of a personal computer via a network or providing a user byfacsimile with the location of a mobile station and information aboutadjacent areas.

[0003] In recent years, mobile devices with a WWW (World Wide Web)browser, which can connect to the Internet, have been commerciallyavailable. Using such a mobile device a user can search for informationabout restaurants and shops in the vicinity of the user, for example, byaccessing a search engine on a web. In these cases, it is veryconvenient to be able to acquire the desired information relating to thepresent location by providing a retrieval server with locationinformation.

[0004] However, because location information is highly confidential itis undesirable to distribute location information on the Internet.

DISCLOSURE OF INVENTION

[0005] The present invention provides a relay center and an informationretrieval method that can search for information on a network byutilizing location information of a mobile station while protecting theprivacy of a user.

[0006] The information retrieval method of the present inventioncomprises (a) a step of acquiring, in a relay center, locationinformation corresponding to a mobile station, the relay center beingconnected to a first network and a second network including the mobilestation, (b) a step of converting, in the relay center, locationinformation acquired in the acquiring step into a character string, (c)a step of proxy retrieval in which the relay center instructs a serverconnected to the first network to search for information relating to thecharacter string and acquires information from the server, (d) a step oftransmitting, by the relay center, information acquired in the proxyretrieval step to the mobile station. The character string represents,for example, an administrative classification corresponding to thelocation information.

[0007] Also, in a preferred form, the relay center includes a databasewhich stores a character string representing location information, andcorresponding information relating to the location. In the case that therelay center searches for information relating to the character stringand does not find corresponding information, the relay center, in thestep of proxy retrieval step, instructs the server to search forinformation relating to the character string.

[0008] Information relating to the character string may include a URL ofthe server providing information.

[0009] A further step may be included wherein, in the step of proxyretrieval step the server is instructed to search for informationrelating to the character string and stores the character string andinformation in the database when the information is acquired from theserver.

[0010] In another preferred form, the second network is a mobilecommunication network; and the location information is identificationinformation of the base station communicating with the mobile stationincluded in the mobile communication network.

[0011] A relay center of the present invention connected to a firstnetwork and a second network including a mobile station comprises (a)means for acquiring location information corresponding to the mobilestation, (b) means for converting acquired location information in theform of a character string, (c) proxy retrieval means instructing theserver connected to the first network to search for information relatingto the character string and acquiring information from the server, and(d) means for transmitting acquired information to the mobile station.

[0012] In another preferred form, the relay center, further including adatabase which stores a character string representing locationinformation and corresponding information relating to the locationinformation, searches the database for information relating to thecharacter string and, in the case that the relay center does not findcorresponding information instructs the server to search for informationrelating to the character string.

[0013] Further, the relay center may instruct the server to search forinformation relating to the character string and store the characterstring and the corresponding information in the database in case theinformation is acquired from the server.

BRIEF DESCRIPTION OF THE DRAWINGS

[0014]FIG. 1 is a block diagram showing the configuration of a mobilecommunication system according to the first embodiment.

[0015]FIG. 2 is a block diagram showing the configuration of mobilestation MS.

[0016]FIG. 3 is a block diagram showing the configuration of gatewayserver GWS.

[0017]FIG. 4a is a diagram showing an example of a source of the mainmenu data.

[0018]FIG. 4b is a diagram showing an example of a displayed image shownon liquid crystal display unit MS4 of a mobile station receiving themain menu data.

[0019]FIG. 5 is a diagram showing area name conversion table TBL.

[0020]FIG. 6 is a diagram showing the memory content of location-relatedinformation database GWS4.

[0021]FIG. 7 is a diagram showing a sequence of a mobile communicationsystem.

[0022]FIG. 8 is a flowchart showing the processing of data distributionmanagement unit GWS3.

[0023]FIG. 9 is a diagram showing an example of a displayed image ofliquid crystal display unit MS4.

[0024]FIG. 10 is a diagram showing an example of a displayed image ofliquid crystal display unit MS4.

[0025]FIG. 11 is a diagram showing the memory content oflocation-related information database GWS4 according to the secondembodiment.

BEST MODE FOR CARRYING OUT THE INVENTION

[0026] Embodiments of the present invention will be explained below withreference to the drawings. These embodiments are communication systemswhich are realized by applying the present invention to a mobilecommunication network connected to the Internet.

[0027] [1] First Embodiment

[0028] [1.1] Configuration of First Embodiment

[0029] (1) Configuration of Entire System

[0030]FIG. 1 is a block diagram showing the configuration of a mobilecommunication system according to the first embodiment. As shown in FIG.1, the mobile communication system comprises a plurality of mobilestations MS, mobile packet communication network MPN, Internet INET, aplurality of IP servers W and so on. For the sake of simplicity, FIG. 1illustrates only one mobile station MS and IP server W among a pluralityof mobile stations MS and IP servers W included in the mobilecommunication system.

[0031] Mobile station MS is a mobile communication terminal such as aportable telephone or a PHS and receives a packet communication serviceof mobile packet communication network MPN and a communication serviceof a mobile telephone network not shown. Mobile station MS comprises avoice input/output unit such as a microphone or a speaker for letting auser carry out voice communication; a transmitter-receiver unit forcarrying out radio communication with a base station of the mobilecommunication network; a liquid crystal display unit utilizing a liquidcrystal panel or the like; a command inputting unit using a PB (pushbutton) or a cursor button and so on, by way of which an informationinputting operation is performed; and a microcomputer for controllingthese various units.

[0032] Mobile packet communication network MPN is for providing mobilestation MS with packet communication service, and comprises base stationBS, packet subscriber processing unit PS, gateway server GWS and so on.

[0033] A multiplicity of base stations BS are installed at predeterminedintervals in the packet communication service area performing radiocommunications with mobile stations MS located in each radio zone. Basestation BS is assigned a base station ID for specifying each basestation BS in mobile packet communication network MPN, and when an upsignal (for example, a GET request of HTTP) is transmitted from mobilestation MS, base station BS adds the base station ID of itself to the upsignal and transmits the signal to packet subscriber processing unit PS.Thus, the base station ID of base station BS is added to the up signaltransmitted from mobile station MS by the time the signal is received bygateway server GWS.

[0034] Packet subscriber processing unit PS is a computer systeminstalled in a packet subscriber switching station including a pluralityof base stations BS and each packet subscriber processing unit PS has aunique packet subscriber processing unit ID. Packet subscriberprocessing unit PS, at the request of mobile station MS for packetswitching, confirms the validity of the received packet switchingrequest, and performs the process of packet switching.

[0035] Gateway server GWS is a computer system installed in the mobilepacket switching station for connecting Internet INET with mobile packetcommunication network MPN and acts as an intermediary for signaltransmission and reception between different networks. Specifically,gateway server GWS adapts a signal transmitted from mobile station MS inmobile packet communication network MPN to TCP/IP (Transmission ControlProtocol/Internet Protocol) for Internet INET by a protocol conversionand transmits the signal to Internet INET. Also, gateway server GWSconverts a signal transmitted from Internet INET so as to adapt to atransmission protocol for the packet communication network and transmitsthe signal to mobile packet communication network MPN.

[0036] According to the present embodiment, gateway server GWSdetermines the present location of mobile station MS on the basis of thesignal transmitted from mobile station MS and sends information aboutthe vicinity of the present location of mobile station MS (hereinafterreferred to as location-related information) to mobile station MS.

[0037] IP (Information Provider) server W is a server on the Internetand stores information to be supplied to the user (for example, a homepage) as HTML data. IP server W has a URL to uniquely specify aninformation resource on the Internet. When this URL is identical to theURL in a received GET request, IP server W transmits informationcorresponding to the URL (i.e., HTML data in HTTP format) to InternetINET.

[0038] (2) Configuration of Mobile Station MS

[0039]FIG. 2 is a block diagram showing the configuration of mobilestation MS according to the first embodiment. As shown in FIG. 2, mobilestation MS comprises a control unit MS1, a transmitter-receiver unitMS2, a command inputting unit MS3, a liquid crystal display unit MS4 anda bus MS5 which interconnects the above units.

[0040] Transmitter-receiver unit MS2 performs radio communications withbase station BS on mobile packet communication network MPN. Commandinputting unit MS3 is equipped with various buttons such as a PB (pushbutton) and a cursor key; and when an inputting operation is performedby a user, command inputting unit MS3 supplies CPU 111 of control unitMS1 with operation data corresponding to the inputting operation. CPU111 determines an inputting command on the basis of the inputtingoperation of the user and performs control corresponding to theinputting command. Liquid crystal display unit MS4 is composed of adisplay device such as a liquid crystal panel, and under the control ofcontrol unit MS1, displays various information. Control unit MSI iscomposed of CPU 111, a ROM 112 and a RAM 113 and controls each unit ofmobile station MS. ROM 112 stores a mobile station ID for uniquelyspecifying mobile station MS in mobile packet communication network MPN,a control program or various control information for controllingthroughout mobile station MS and a WWW browser program for obtainingdata from IP server W and displaying a character and an image. RAM 113is used as a work area of CPU 111. CPU 111 carries out various kinds ofprocessing by reading out various control programs stored in ROM 112.For example, when CPU 111 reads out a WWW browser stored in ROM 112, andthe user inputs a URL by way of command inputting unit MS3, CPU 111transmits a GET request of HTTP including the URL to mobile packetcommunication network MPN. Further, when HTML data corresponding to theGET request is returned from IP server W or gateway server GWS, CPU 111writes the HTML data in RAM 113 and displays the image represented bythe data in liquid crystal display unit MS4.

[0041] (3) Configuration of Gateway Server GWS

[0042]FIG. 3 is a block diagram showing the configuration of gatewayserver GWS. As shown in FIG. 3, gateway server GWS comprises a systemcontrol unit GWS1, a subscriber information management unit GWS2, a datadistribution management unit GWS3 and a bus GWS5 interconnecting theseunits.

[0043] Subscriber information management unit GWS2 stores and managesinformation relating to a subscriber of a packet communication serviceusing mobile packet communication network MPN (for example, a telephonenumber or a mail address of each mobile station MS, attributeinformation of a subscriber and so on). System control unit GWS1controls each unit of gateway server GWS and functions as an interfacebetween different networks and performs the protocol conversion betweenmobile packet communication network MPN and Internet INET or othernetworks. System control unit GWS1, upon receiving a GET request frommobile station MS in mobile packet communication network MPN, carriesout a search for a URL included in the GET request, and, in the casethat the URL is a general URL on Internet INET (for example, a URLshowing an information resource location in IP server W), and systemcontrol unit GWS1 converts the protocol of the GET request and transfersthe converted protocol to Internet INET. Also, in the case that the URLincluded in the GET request represents an information resource locationin gateway server GWS, system control unit GWS1 transmits the GETrequest to data distribution management unit GWS3. Data distributionmanagement unit GWS3 stores information such as a home page or a webpage to be distributed to mobile station MS and, according to a GETrequest transmitted from system control unit GWS1, distributes datacorresponding to the GET request to mobile station MS. For example, incase that the GET request including the URL corresponding to a home pageof gateway server GWS is transmitted from mobile station MS, datadistribution management unit GWS3, according to the GET request,distributes data in HTML format (hereinafter referred to as “menu data”)to mobile station MS.

[0044]FIG. 4a is a diagram showing an example of a source of the menudata. FIG. 4b is a diagram showing an example of a displayed image shownon liquid crystal display unit MS4 of mobile station MS obtaining themenu data. In FIG. 4a, <A herf=“ ”></A>is an anchor tag and shows theURL of a service item which gateway server GWS can provide to mobilestation MS (hereinafter referred to as “menu item”).

[0045] The URL corresponding to each menu item shows a location ofinformation in gateway server GWS (web page). When a GET requestcontaining a URL included in the menu data is transmitted from mobilestation MS, gateway server GWS returns submenu data corresponding to theURL. The submenu data is data in an HTML format such as menu data andincludes the service information corresponding to each menu item(hereinafter referred to as “submenu item”). The data also includes theURL corresponding to each submenu item.

[0046] Specifically, as shown in FIG. 4b, when mobile station MSreceives menu data, the character or the image representing each menuitem, for example, “location-related information service”, “newsservice” and so on is displayed. “Location-related information service”is the service for providing information about shops or facilities inthe vicinity of mobile station MS. The submenu item of “location-relatedinformation service” includes “restaurant information”, “movie theaterinformation” and “shop information”; “restaurant information” includesrestaurants in the vicinity of the user (“restaurant A”, “restaurant B”,. . . ) as well as information for acquiring information relating tothese restaurants (URL, telephone number, etc.).

[0047] Data distribution management unit GWS3 includes area nameconversion table TBL and location-related information database GWS4.FIG. 5 is a diagram showing area name conversion table TBL, and FIG. 6is a diagram showing the memory content of location-related informationdatabase GWS4. As shown in FIG. 5, area name conversion table TBL storesthe “base station ID” and the “area name” representing the area of basestation BS which corresponds with the base station ID. For example, ifthe address of each of the items in base station ID group “BS001 toBS005” contains “1-chome, Shibuya, Shibuya-ku, Tokyo”, “1-chome,Shibuya” as an area name is stored.

[0048] On the other hand, location-related information database GWS4, asshown in FIG. 6, stores location-related information corresponding toeach submenu item which is composed of store names, area names oflocations of shops, and a URL of a link site providing telephone numbersand other information of the shops. For example, in the case shown inFIG. 6, a shop name “restaurant A”, an area name “1-chome, Shibuya”, aURL “http://www.aa.nejp” and a telephone number “03-1111-1111” arestored as location-related information corresponding to the submenu item“restaurant information”. Each area name stored in location-relatedinformation database GWS4 and each area name stored in area nameconversion table TBL are area names classified by the same method.

[0049] Storing the location-related information may be performed by anyof several methods. For example, IP server W may store information byaccessing gateway server GWS, data distribution management unit GWS3 mayaccess IP server W and extract a keyword relating to location-relatedinformation such as an area name or a shop name or the like and storethe information in location-related information database GWS4. In thiscase, it is desirable that an update of information is performedperiodically.

[0050] In the case that a GET request of HTTP transmitted from mobilestation MS includes a URL of each submenu item of “location-relatedinformation service”, data distribution management unit GWS3 extractsthe base station ID which base station BS adds to the GET request.Further, data distribution management unit GWS3 reads out the area namefrom area name conversion table TBL, the area name corresponding to thebase station ID extracted from the GET request. Data distributionmanagement unit GWS3 extracts location-related information including thearea name read out from location-related information database GWS4 anddistributes the information to mobile station MS.

[0051] A data format of location-related information to be stored inlocation-related information database GWS4 can take an arbitrary form,but data transmitted from gateway server GWS to mobile station MS mustbe HTML data. Thus, in the case that the data format of location-relatedinformation is not in an HTML format, a conversion of the data format isperformed by gateway server GWS.

[0052] [1.2] Operation of First Embodiment

[0053] The operation of the mobile communication system according to thepresent embodiment will be explained below. First, when the userperforms a predetermined operation on command inputting unit MS3 ofmobile station MS, CPU 111 reads out a WWW browser from ROM 112.Further, CPU 111, according to the WWW browser, carries out theprocessing for a packet registration for packet subscriber processingunit PS. The packet registration is the registration procedure forpacket switching between mobile station MS and mobile packetcommunication network MPN.

[0054] Next, CPU 111 transmits a connection establishment request tomobile packet communication network MPN via transmitter-receiver unitMS2. The connection between mobile station MS and gateway server GWS isestablished, and mobile station MS can perform packet switching withgateway server GWS.

[0055] Then, the user inputs a URL of a home page of gateway server GWSby way of command inputting unit MS3 of mobile station MS, and theprocessing shown in FIG. 7 is carried out. First, CPU 111 of mobilestation MS transmits the GET request of HTTP including the URL of thehome page of gateway server GWS to transmitter-receiver unit MS2.Consequently, the GET request is transmitted to base station BS bytransmitter-receiver unit MS2 (step Sa1). Base station BS receives theGET request and adds the base station ID of itself to the GET requestand transmits the request to gateway server GWS (step Sa2).

[0056] System control unit GWS1 of gateway server GWS, upon receivingthe GET request, determines that the URL included in the GET requestrepresents its own home page and transmits the GET request to datadistribution management unit GWS3. Data distribution management unitGWS3 which receives the GET request transmits menu data to systemcontrol unit GWS1. The menu data is transmitted from system control unitGWS 1 to mobile station MS via base station BS (step Sa3).

[0057] Transmitter-receiver unit MS2 of mobile station MS, uponreceiving the menu data, transmits the data to CPU 111 (step Sa4).Further, CPU 111 stores the menu data transmitted fromtransmitter-receiver unit MS2 in RAM 113, and displays in liquid crystaldisplay unit MS4 an image corresponding to the menu data. That is, alist of services which mobile station MS can obtain, as shown in FIG.4b, is displayed in liquid crystal display unit MS4.

[0058] In this situation, the user performs an inputting operation oncommand inputting unit MS3 to select the menu item “location-relatedinformation service”, and CPU 111 extracts the URL corresponding to“location-related information service”, that is“http://www.gws.ne.jp/aa”, from the menu data. Further, CPU 111transmits the GET request including the extracted URL totransmitter-receiver unit MS2. Then, the GET request is transmitted togateway server GWS via base station BS by transmitter-receiver unit MS2(steps Sa5, Sa6).

[0059] The GET request is received by system control unit GWS1 andtransmitted to data distribution management unit GWS3. Data distributionmanagement unit GWS3 extracts a URL from the GET request and determinesthat the URL is the URL corresponding to the menu item “location-relatedinformation service” and initiates the processing shown in FIG. 8.

[0060] First, data distribution management unit GWS3 transmits thesubmenu data corresponding to the menu item “location-relatedinformation service” to system control unit GWS1 (step Sb1 in FIG. 8).System control unit GWS1 transmits the submenu data to mobile station MSvia base station BS (steps Sa7, Sa8). Then, processing in datadistribution management unit GWS3 goes to step Sb2 in FIG. 8. Until anext GET request including a URL corresponding to submenu item frommobile station MS is received, a determination in step Sb2 in FIG. 8remains “No”.

[0061] The submenu data transmitted from gateway server GWS is receivedby transmitter-receiver unit MS2 and transmitted to CPU 111. CPU 111stores the submenu data in RAM 113 and displays the image represented bythe data in liquid crystal display unit MS4.

[0062]FIG. 9 is a diagram showing an example of an image displayed inliquid crystal display unit MS4 of mobile station MS at the time ofreceiving the submenu data. In the situation shown in FIG. 9, forexample, the user operates the cursor key of command inputting unit MS3,and the submenu item selected provisionally is highlighted. In FIG. 9,“restaurant information” is provisionally selected. In this situation,the user presses the decision button of command inputting unit MS3, andCPU 111 reads out the URL corresponding to “restaurant information” andtransmits the GET request of HTTP including the URL to base station BS(step Sa9).

[0063] Base station BS, upon receiving the GET request transmitted frommobile station MS, adds its own base station ID to the GET request andtransmits the request to gateway server GWS (step Sa10).

[0064] Then, the GET request transferred from base station BS isreceived by system control unit GWS1 and transmitted to datadistribution management unit GWS3. In this manner, the GET requestincluding the URL corresponding to the submenu item “restaurantinformation” is transmitted from system control unit GWS1, and adetermination in step Sb2 in FIG. 8 becomes “Yes”. Next, datadistribution management unit GWS3 extracts the base station ID from theGET request (step Sb3 in FIG. 8).

[0065] Then, data distribution management unit GWS3 reads out the areaname corresponding to the base station ID extracted from area nameconversion table TBL (step Sb4 in FIG. 8). For example, in the case thatthe base station ID is “BS001”, the area name “1-chome, Shibuya” is readout (see FIG. 5).

[0066] Next, data distribution management unit GWS3, using the area name“1-chome, Shibuya” as a search key, searches location-relatedinformation database GWS4 for location-related information correspondingto “restaurant information” (step Sb5 in FIG. 8).

[0067] In a case that the corresponding location-related informationdoes not exist, a determination in step Sb6 in FIG. 8 becomes “No”. Inwhich case, data distribution management unit GWS3 transmits to mobilestation MS (step Sb9 in FIG. 8) the fact that the correspondinglocation-related information does not exist. As a result, a message suchas “corresponding information is not found” or the like is displayed inliquid crystal display unit MS4 of mobile station MS.

[0068] In the case that the corresponding location-related informationexists (step Sb6 “Yes” in FIG. 8), that is, in the case that thelocation-related information including “1-chome, Shibuya” as an areaname exists, data distribution management unit GWS3 transmits thelocation-related information to system control unit GWS1 fortransmission to mobile station MS (steps Sb7, Sb8 in FIG. 8).

[0069] For example, in the case that the location-related informationstored in location-related information database GWS4 is the content asshown in FIG. 6, data distribution management unit GWS3 reads outlocation-related information corresponding to “restaurant A” or thelike, that is the URL of a site providing information relating to“restaurant A” and a telephone number and so on of “restaurant A”, aslocation-related information corresponding to “1-chome, Shibuya” (stepSb7 in FIG. 8) and transmits the information to system control unit GWS1(step Sb8 in FIG. 8). The URL and the telephone number, etc. aretransmitted to mobile station MS via base station BS (steps Sa11, Sa12).

[0070] The location-related information transmitted from gateway serverGWS is received by transmitter-receiver unit MS2 and transmitted to CPU111. Then, CPU 111 writes the location-related information transmittedfrom transmitter-receiver unit MS2 in RAM 113 and displays the image ofthe location-related information in liquid crystal display unit MS4.

[0071]FIG. 10 is a diagram showing an example of an image displayed inliquid crystal display unit MS4 of mobile station MS.

[0072] “Restaurant A” is provisionally selected, and a character stringof “restaurant A” is highlighted. The user then presses the decisionbutton of command inputting unit MS3, and CPU 111 reads out the URLcorresponding to “restaurant A”, that is “http://www.aa.ne.jp” (see FIG.6), and transmits the GET request of HTTP including the URL totransmitter-receiver unit MS2. Consequently, the GET request istransmitted to gateway server GWS via base station BS bytransmitter-receiver unit MS2 (steps Sa13, Sa14).

[0073] System control unit GWS1 of gateway server GWS, upon receivingthe GET request, determines that the URL included in the GET request isnot its own URL and transfers the GET request to Internet INET (stepSa15).

[0074] IP server W, upon receiving the GET request transferred toInternet INET, returns HTML data corresponding to the URL included inthe GET request (in this case, HTML data relating to “restaurant A”) toInternet INET. As a result, the HTML data is transmitted to mobilestation MS via gateway server GWS (steps Sa16, Sa17, Sa18).

[0075] In this manner, a gateway server in the mobile communicationsystem according to the present embodiment, using the base station ID ofa base station including a mobile station, acquires the present locationof the mobile station and transmits the location-related informationcorresponding to the present location. Thus, the user can acquireinformation relating to the present location provided by an IP serverwithout transmitting the present location of the user to an IP server(i.e. without distributing the present location on the Internet).

[0076] [1.3] Modifications

[0077] <Modification 1-1>

[0078] According to the present embodiment, gateway server GWS, usingthe base station ID included in a signal transmitted from mobile stationMS, acquires the present location of the user. The invention is notlimited to the procedure of acquiring location information. It is alsopossible to acquire the present location of the user by installing a GPSin mobile station MS and transmit the latitude and longitude of thepresent location acquired by using the GPS to the gateway server GWS. Inthis case, information of the latitude and longitude corresponding toeach area name instead of a base station ID is stored in area nameconversion table TBL.

[0079] Another method would be to equip mobile station MS with afunction for measuring the electrical field reception strength and theelectrical field reception strength of beacon signals transmitted fromthree different base stations and transmit the discrete values of themeasured strengths of the two electric field receptions and the basestation ID to gateway server GWS. In this case, gateway server GWScomputes the present location of mobile station MS on the basis of thetransmitted electrical field reception strength and the base station ID.Alternatively, a method for classifying each area may be based not onlyon an address but also on a zip code, latitude, longitude, and so on.

[0080] <Modification 1-2>

[0081] According to the present embodiment, location-related informationdatabase GWS4 is installed in gateway server GWS, and retrieval oflocation-related information is performed in gateway server GWS. But,the location-related information database may also be installed in theretrieval server on Internet INET and the retrieval server may searchfor location-related information.

[0082] In this case, gateway server GWS, after reading out the area namecorresponding to a base station ID, transmits only the area name to theretrieval server on Internet INET. The retrieval server, using the areaname transmitted in this manner as a search key, performs a retrievaland returns the extracted location-related information to gateway serverGWS. Gateway server GWS transmits the location-related informationreturned from the retrieval server to mobile station MS. At this stage,data distribution management unit GWS3 may use a predetermined code orthe like to link the location-related information transmitted from theretrieval server with mobile station MS which has requested thelocation-related information.

[0083] Specifically, for example, in the case that the GET requestcorresponding to the submenu item “restaurant information” istransmitted from mobile station MS, data distribution management unitGWS3 produces the predetermined code for the GET request and adds thecorrespondent code to an area name and transmits the area name to theretrieval server. The retrieval server adds the correspondent code tothe extracted location-related information and transmits theinformation. Then, data distribution management unit GWS3 specifieswhich mobile station MS will receive the location-related informationbased on the correspondent code and transmits the information to mobilestation MS.

[0084] In this manner, a configuration that allows a retrieval ofinformation to be performed in the retrieval server on the Internetenables the gateway server to reduce the burden of processing.Alternatively, only an area name and a correspondent code aretransmitted to Internet INET. Because information by which the user canbe specified does not exist, if another person illegally acquires anarea name or a correspondent code on Internet INET, user privacy isprotected.

[0085] [2] Second Embodiment

[0086] Because the configuration and the operation of the mobilecommunication system according to the second embodiment is the same asthose of the first embodiment, an explanation will be omitted. Themethod of storing information in location-related information databaseGWS4 is different from that of the first embodiment. FIG. 11 is adiagram showing the memory content of location-related informationdatabase GWS4 according to the second embodiment. Unlike the firstembodiment shown in FIG. 6, location-related information database GWS4according to the second embodiment stores unalike submenu datacorresponding to each area name stored in area name conversion tableTBL. Specifically, the data of submenu items corresponding to the areaname “1-chome, Shibuya” includes “restaurant information”, “movietheater information”, “shop information” and so on; and the submenu item“restaurant information”, for example, stores information relating torestaurants in “1-chome, Shibuya, the URL of a site providinginformation relating to “restaurant A” or the telephone number of“restaurant A”, etc.

[0087] Location-related information database GWS4 according to thepresent embodiment has a submenu item for every area name; on acquiringan area name gateway server GWS can quickly read out correspondinglocation-related information. That is, unlike in the first embodiment,using an area name as a search key is not needed in the secondembodiment for searching location-related information database GWS4.Thus, the burden of processing associated with the retrieval function inthe gateway server is reduced, and the second embodiment makes possiblea quick response to a request of location information by the user.

[0088] The invention is not limited to specific configurations of theabove-mentioned embodiments and can take various forms within theconfines of claims.

1. An information retrieval method, comprising the steps of: acquiring, in a relay center, location information corresponding to a mobile station, said relay center being connected to a first network and a second network including said mobile station; converting, in said relay center, location information acquired in said acquiring step into a character string; a proxy retrieval process in which said relay center instructs a server connected to said first network to search for information relating to said character string and acquires said information from said server; and transmitting, by said relay center, said information acquired in said proxy retrieval process step to said mobile station.
 2. An information retrieval method according to claim 1, wherein said character string represents an administrative classification corresponding to said location information.
 3. An information retrieval method according to claim 1, wherein: said relay center comprises a database which stores said character string representing said location information and information relating to said location information in correspondence with each other; and said relay center, in said proxy retrieval process step, searches said database for information relating to said character string and, in a case that corresponding information is not found, instructs said server to search for information relating to said character string.
 4. An information retrieval method according to claim 1, wherein information relating to said character string includes information representing a location in which said information is stored.
 5. An information retrieval method according to claim 3, further comprising the steps of: instructing said server to search for information relating to said character string in said proxy retrieval process step; and storing said character string and said information in said database in correspondence with each other in a case that said information is acquired from said sever.
 6. An information retrieval method according to claim 1 or 3, wherein said second network is a mobile communication network, said location information is identification information of a base station which communicates with said mobile station and is included in said mobile communication network.
 7. A relay center connected to a first network and a second network including a mobile station, comprising: means for acquiring location information corresponding to said mobile station; means for converting said acquired location information into a character string; proxy retrieval means for instructing a sever connected to said first network to search for information relating to said character string and acquiring said information from said server; and transmitting said acquired information to said mobile station.
 8. A relay center according to claim 7, further comprising a database which stores said character string representing location information and information relating to said location information in correspondence with each other, wherein said relay center searches said database for information relating to said character string, in a case that corresponding information is not found, instructs said server to search for information relating to said character string.
 9. A relay center according to claim 8, wherein said relay center instructs said server to search for information relating to said character string and, in a case that said information is acquired from said server, stores said character string and said information in said database in correspondence with each other. 